Many industrial applications produce steam, employ the steam in a process or apparatus, and condense the steam back to water. The condensate water is typically recycled back to the steam production in a closed cycle, rather than being discharged. The recycling of the condensate is undertaken because the water may be treated with expensive chemicals that would be lost if the water were discharged, because the discharge of the water could have adverse environmental consequences, and because the heat of the hot water would be lost if it were discarded.
To recycle the condensate, it is accumulated in a condensate reservoir and pumped back to the boiler under pressure. Condensate water enters the reservoir until the reservoir is nearly full, and then the condensate is pumped out of the reservoir by a compressed gas such as steam or compressed air. At the completion of the pump-out when the liquid level is low, the reservoir is vented, and the accumulation process repeats.
A number of different approaches have been utilized for the pump used in conjunction with the condensate reservoir. Historically and in the majority of current applications, a centrifugal pump is used. More recently, the steam-pumping trap has been introduced. The steam-pumping trap typically employs a spring-loaded overcenter or other type of mechanism to open and close the pressure and vent valves in coordination with a float that senses the liquid level in the reservoir. The valves use a plug-and-seat configuration. While operable, such designs have associated high fabrication and maintenance costs. Additionally, the sizes of the pressure and vent ports are limited. Because of the large forces required to operate the mechanism, the float must be relatively large in size.
There is a need for an improved approach to the construction of the condensate pump that overcomes these limitations. The present invention fulfills this need, and further provides related advantages.